Find the equation of the line with slope 0 and y-intercept
(0, -2). Write your answer in the form y = mx + b. 

A line with slope 0 is horizontal. if it goes through (0, -2) 
then every point on it has the same y-coordinate.  Therefore 
the equation y = -2 tells the whole story of every y-value of 
every point on the line. Here is a picture of the line. 
It's the green one below.



Notice that every point on the green line has -2 as its 
y-coordinate, and it intercepts the y-axis at -2, so 
b = -2 and m = 0,

So to write it in the form 

y = mx + b

you write it as

y = 0x - 2

which is the same as y = -2

Edwin